In the USA, every year, 500,000 cases of genital warts are discovered, caused in 90% of cases by type 6 and 11 Papillomavirus, while serotypes 16 and 18 are accountable for 70% of cervical cancers. Since 2006 a quadrivalent vaccine (HPV4) is available, containing all the 4 serotypes and put to the disposal of female population between 9 and 26 years of age. In October 2009, a new vaccine has been marketed for women and FDA has authorized the use of HPV4 also in males. The new vaccine (HPV2) is a bivalent vaccine with an action against serotypes 16 and 18, advised for girls between 10 and 25 years of age: in clinical trials, the vaccine has been shown to have a preventive efficacy of 93% towards stage-2 and stage-3 cervical intraepithelial cancer lesions and towards adenocarcinoma in situ, but not having efficacy in patients resulting positive to HPV 16 or 18 before vaccination. Side reactions have been above all local reactions in the seat of injection (pain, reddening, swelling), while severe reactions have been similar to the ones found in the control group. The administration schedule of HPV2 and HPV4 are similar, but it is opportune to use always the same kind of vaccine, since interchange has not been shown yet. HPV4 vaccine has been now approved also for its use in males between 9 and 26 years of age, as a prevention against genital warts caused by HPV 6 and 11. The preventive efficacy of three administrations in seronegative males reaches 90%. The administration schedule and side effects are the same as female ones.
Having two vaccines at one’s disposal, now the problem the general practitioner has is to choose the kind of vaccine: HPV4 is more complete, but many patients prefer to use less possible viral strains. No doubt, it is necessary to warn potential addressees that the vaccine has no action on an existing HPV infection. In spite the vaccine is available now also for males, the best strategy to contrast the spreading of HPV-related lesions remains to vaccinate all females at the age of 11-12. For males, it is probably necessary to vaccinate the ones having very risky sexual behaviours.
